U.S. patent application number 13/106773 was filed with the patent office on 2012-06-07 for control method of hybrid power battery charger.
This patent application is currently assigned to Texas Instruments Incorporated. Invention is credited to Suheng Chen, Qiong M. Li, Jinrong Qian, Richard Stair, Mao Ye.
Application Number | 20120139345 13/106773 |
Document ID | / |
Family ID | 46161537 |
Filed Date | 2012-06-07 |
United States Patent
Application |
20120139345 |
Kind Code |
A1 |
Ye; Mao ; et al. |
June 7, 2012 |
CONTROL METHOD OF HYBRID POWER BATTERY CHARGER
Abstract
A power supply system and method for operating same. The power
supply system is connectable to receive power from an adapter and
supply power to a load. The power supply system includes a
rechargeable battery, a buck mode circuit, and a boost mode
circuit. A switching circuit switches between the buck mode circuit
and boost mode circuit for supplying power to the load. If the
power required by the load reaches a first predetermined level
related to an adapter overload condition for a first predetermined
time, the switching circuit disconnects said buck mode circuit from
the load and connects the rechargeable battery and the boost mode
circuit to said load. The first predetermined level may be
established by a first predetermined percent of the current of a
dynamic power management level established by the load, which is
related to a power level below that which can be provided by the
adapter.
Inventors: |
Ye; Mao; (Plano, TX)
; Stair; Richard; (Knoxville, TN) ; Chen;
Suheng; (Knoxville, TN) ; Qian; Jinrong;
(Plano, TX) ; Li; Qiong M.; (Allen, TX) |
Assignee: |
Texas Instruments
Incorporated
Dallas
TX
|
Family ID: |
46161537 |
Appl. No.: |
13/106773 |
Filed: |
May 12, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61418616 |
Dec 1, 2010 |
|
|
|
61479284 |
Apr 26, 2011 |
|
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Current U.S.
Class: |
307/66 |
Current CPC
Class: |
H02J 2207/20 20200101;
H02M 1/10 20130101; H02M 1/32 20130101; H02J 7/0063 20130101; H02J
7/0068 20130101; H02M 3/1582 20130101; Y02T 90/12 20130101 |
Class at
Publication: |
307/66 |
International
Class: |
H02J 9/04 20060101
H02J009/04 |
Claims
1. A power supply system connectable to receive power from an
adapter and supply power to a load, comprising: a rechargeable
battery; a buck mode circuit; a boost mode circuit; and a switching
circuit for switching between said buck mode circuit and boost mode
circuit for supplying power to the load; wherein if the power
required by the load reaches a first predetermined level related to
an adapter overload condition for a first predetermined time, said
switching circuit disconnects said buck mode circuit from said load
and connects said rechargeable battery and said boost mode circuit
to said load.
2. The power supply system of claim 1 wherein said first
predetermined level is established by a first predetermined percent
of the current of a dynamic power management level established by
the load, which is related to a power level below that which can be
provided by the adapter.
3. The power supply system of claim 2 wherein said first
predetermined percent of the current of a dynamic power management
level established by the load is about 105%.
4. The power supply system of claim 1 wherein if the power required
by the load is below a second predetermined level related to the
adapter overload condition for a second predetermined time and the
boost mode circuit and rechargeable battery are connected to the
load, said boost mode circuit and said rechargeable battery are
disconnected from the load and said buck mode circuit is
started.
5. The power supply system of claim 4 wherein if the power required
by the load is below a third predetermined level related to the
adapter overload condition and the boost mode circuit and
rechargeable battery are connected to the load, said boost mode
circuit and said rechargeable battery are disconnected from the
load and said buck mode circuit is started, said third
predetermined level being less than said second predetermined
level.
6. In a power supply system connectable to a load, said power
supply system having a rechargeable battery, a charging circuit,
and an adapter connectable to receive power from a power supply
source, said charging circuit comprising: buck mode circuitry for
selectively supplying power to the load in a normal operating mode;
boost mode circuitry for selectively supplying power to the load in
an adapter overload operating mode; and switching circuitry for
switching between said buck mode circuitry and boost mode
circuitry; wherein if the power required by the load reaches an
adapter overload condition, said charging circuit shuts down, and
waits a predetermined time; wherein after the predetermined time,
the charging circuit checks to determine whether the adapter
overload condition still exists; wherein if the adapter overload is
still exists, said charging circuit changes from said buck mode
circuitry to said boost mode circuitry and connects said battery to
the load to provide additional power to the load.
7. The power supply system of claim 6 wherein said check to
determine whether the adapter is still in the adapter overload
condition is based on a system current.
8. The power supply system of claim 6 wherein said adapter overload
condition is sensed by a programmable current threshold
circuit.
9. The power supply system of claim 6 further comprising an adapter
over-voltage protection circuit to disable the boost mode circuitry
to prevent said boost mode circuitry from generating too high of a
voltage on the load.
10. The power supply system of claim 6 further comprising a
watchdog timer configured to change from said boost mode circuitry
to said buck mode circuitry after a preset time.
11. The power supply system of claim 6 further comprising a control
loop saturation detecting circuit to stop a boost mode operation if
a control loop saturates and an adapter current is above a
predetermined level.
12. A method for operating a charger circuit having a rechargeable
battery, a buck mode circuit, and a boost mode circuit, comprising:
operating said buck mode circuit to provide power to a load in a
normal operating mode; sensing an input current to said charger
circuit; if said input current exceeds a first predetermined
percent of a current of a dynamic power management level
established by the load, shutting down the charger circuit for a
first predetermined time; and if said input current continues to
exceed the first predetermined percent of a current of a dynamic
power management level established by the load after the first
predetermined time, starting the boost mode circuit and connecting
the rechargeable battery to provide power to the load.
13. The method of claim 12 wherein said first predetermined time is
at least 100 .mu.s.
14. The method of claim 12 wherein said dynamic power management
level is an input current level established to operate said load in
a manner to protect said adapter from an overload condition.
15. The method of claim 12 wherein if the input current is less
than a first predetermined level, stopping said boost mode circuit,
disconnecting said rechargeable battery from the load, and starting
said buck mode circuit.
16. The method of claim 15 wherein said predetermined amount is
less than about 1 A for a 10 milliohm sensing resistor.
17. The method of claim 15 wherein if the input current is above
said first predetermined level and less than a second predetermined
percent of the current of a dynamic power management level
established by the load for a second predetermined time, stopping
said boost mode circuit, disconnecting said rechargeable battery
from the load, and starting said buck mode circuit.
18. The method of claim 17 wherein said second predetermined time
is about 1 ms.
19. The method of claim 17 wherein said first predetermined amount
is greater than 1 A for a 10 milliohm sensing resistor.
20. The method of claim 17 wherein said second predetermined
percent is less than about 93 percent of the dynamic power
management level established by the load.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/418,616, filed Dec. 1, 2010, and
also claims the benefit of U.S. Provisional Patent Application Ser.
No. 61/479,284, filed Apr. 26, 2011, both of which are assigned to
the assignee hereof and incorporated herein by reference in their
entireties.
FIELD
[0002] The various circuit embodiments described herein relate in
general to battery charging and controlling circuits and methods,
and, more specifically, to battery charging and controlling
circuits and methods in which current can be drawn from both a
charging adapter and the battery in response to a high load demand
for current.
BACKGROUND
[0003] Rechargeable batteries, typically lithium-ion batteries, are
widely used in consumer electronic devices, especially portable
computers and mobile devices. Although examples of devices with
which such batteries may be used are manifold, some recent examples
include smartphone, notebook, tablet, and netbook computing
devices, or the like, which have a CPU and memory that require
operating power. When the device is not powered by the battery, an
adapter is commonly used to power the device with which the battery
is associated. At the same time, the adapter provides power to a
charging circuit in the device to charge the battery. In such
charging circuits, a synchronous switching buck converter is often
used to control the charging current to the battery, while
providing a substantially constant voltage to the load.
[0004] Traditionally, when the power required by the CPU and system
load increase to reach the adapter power limit, the charge current
can be reduced to zero, thereby giving a higher priority to power
the system than to charge the battery. However, in certain
conditions, if the CPU power demands are greater than those that
can be met by the adapter, the adapter may crash. An example of
such condition is when the system is cold and the CPU power needed
for application processing and speeding up data flow is much more
than the power that the adapter can supply, even with zero charging
current.
[0005] In the past, several solutions to the problem have been
advanced. For example, one solution disables the CPU high current
mode. This, however, lowers the system performance. Another
solution uses an adapter with an increased current capability.
This, however, increase the adapter cost. Yet another solution
reduces the system bus voltage. This, however, is not a widely
adopted battery charger solution, and is not suitable for a high
power system. Still another solution is to add an additional boost
converter and include a boost controller. This, however, requires
at least a power MOSFET, diode, and other circuit components. The
cost of this solution, however, is high and needs more space.
[0006] Thus, in order to solve the problem of operating a CPU at a
high speed to improve the system performance, while not crashing
the adapter, it has been suggested to use the battery and adapter
to simultaneously power the system when power demands are high. One
way in which this has been done has been to use a boost converter
in the charging circuit to convert the battery power for delivery
to the system. The charger can operate in a synchronous buck mode
during the battery charging and in a boost mode when additional
power to CPU and system is needed. This type of charging circuit is
referred to herein as a "hybrid power battery charger."
[0007] What is needed is a system and method that uses the battery
charger as a boost converter to boost battery voltage to adapter
voltage and control method for achieving smooth mode transition
between buck charging mode and boost supplement mode, and optimized
efficiency.
SUMMARY
[0008] The proposed system and method described herein uses the
existing battery charger configuration, but a control method is
used that allows the charger to operate in a hybrid mode in which
the charger operates in a buck mode during battery charging and in
a boost mode during the battery discharging to supplement
additional power to the system. This allows the CPU to operate at
very high speed to realize its highest performance. In addition,
the system does not need to increase the adapter current
capability, thereby avoiding extra cost to the adapter. It realizes
high power conversion efficiency, low total system cost, with a
minimum space requirement.
[0009] Thus, according to one embodiment of a power supply system
that is connectable to receive power from an adapter and supply
power to a load, a rechargeable battery, a buck mode circuit, and a
boost mode circuit are provided. A switching circuit is provided
for switching between the buck mode circuit and boost mode circuit
for supplying power to the load. If the power required by the load
reaches a first predetermined level related to an adapter overload
condition for a first predetermined time, the switching circuit
disconnects said buck mode circuit from the load and connects the
rechargeable battery and the boost mode circuit to said load. The
first predetermined level may be established by a first
predetermined percent of the current of a dynamic power management
level established by the load, which may be related to a power
level below that which can be provided by the adapter.
[0010] According to another embodiment of a power supply system
connectable to a load, a power supply system having a rechargeable
battery, a charging circuit, and an adapter connectable to receive
power from a power supply source are provided. The charging circuit
includes buck mode circuitry for selectively supplying power to the
load in a normal operating mode and boost mode circuitry for
selectively supplying power to the load in an adapter overload
operating mode. Switching circuitry is provided for switching
between the buck mode circuitry and the boost mode circuitry. If
the power required by the load reaches an adapter overload
condition, the charging circuit shuts down and waits a
predetermined time. After the predetermined time, the charging
circuit checks to determine whether the adapter overload condition
still exists, and if the adapter overload is still exists, the
charging circuit changes from the buck mode circuitry to the boost
mode circuitry and connects the battery to the load to provide
additional power to the load. The check to determine whether the
adapter is still in the overload condition may be based, for
example, on a system current.
[0011] According to an embodiment of a method for operating a
charger circuit having a rechargeable battery, a buck mode circuit,
and a boost mode circuit, the buck mode circuit is operated to
provide power to a load in a normal operating mode. An input
current to the charger circuit is sensed. If the input current
exceeds a first predetermined percent of a current of a dynamic
power management level established by the load, the charger circuit
is shut down for a first predetermined time. If the input current
continues to exceed the first predetermined percent of a current of
a dynamic power management level established by the load after the
first predetermined time, the boost mode circuit is started and the
rechargeable battery is connected to provide power to the load.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a block diagram of an example of a hybrid battery
charger environment in which battery charging and controlling
circuits and methods described herein may be employed.
[0013] FIG. 2 is an electrical schematic diagram illustrating an
example of an embodiment of a charger circuit having a voltage
boost function that may be used in the battery charging and
controlling circuits and methods described herein.
[0014] FIG. 3A is a block diagram of an example of feedback
amplifier, duty cycle, and driver circuits for implementing the
battery charging and controlling circuits and methods of FIG.
2.
[0015] FIG. 3B is a block diagram of an example of start/stop
control circuits for implementing the battery charging and
controlling circuits and methods of FIG. 2.
[0016] FIG. 4 is a flow chart illustrating one embodiment of a
method for operating the circuit of FIG. 2 to enter a boost mode of
operation.
[0017] FIG. 5 is a flow chart illustrating one embodiment of a
method for operating the circuit of FIG. 2 to exit a boost mode of
operation.
[0018] And FIGS. 6A-6D are waveforms of various parameters verses
time realized in the operation of the circuit of FIG. 2.
[0019] In the various figures of the drawing, like reference
numbers are used to denote like or similar parts.
DETAILED DESCRIPTION
[0020] A block diagram of an example of a hybrid battery charger
environment 10 is shown in FIG. 1. The hybrid battery charger
environment 10 includes a system 12, which may be, for instance, a
smartphone, notebook, tablet, netbook computing devices, or the
like, which has a CPU 14 and a memory 16 that require operating
power. The CPU 14 and memory 16 are part of the system load 18 for
which the operating power is needed. The operating power to the
system load is provided by a buck/boost charger system 20 and an
associated rechargeable battery pack 22, in a manner described
below in greater detail. The rechargeable battery pack 22 may be a
lithium-ion battery pack, for example, although other rechargeable
battery types may also be employed.
[0021] An adapter 24 is provided, which is optionally connectable
to receive ac power, typically from an ac outlet, not shown, to
convert the ac power to dc power to supply power to the buck/boost
charger system 20 to power the system load 18 and to charge an
associated rechargeable battery pack 22. For example, depending on
the particular power requirements of a particular system load 18, a
typical adapter may supply 90 W of power at about 20 V, thereby
having the capability of supplying about 4.5 A current. The
adapters, of course are load dependent, and may vary greatly from
one application to another; however, one of the advantages of the
hybrid battery charger of the type described herein is that the
power requirements of the particular adapter needed can be reduced
from that which would be required if the adapter alone is used to
supply operating power to the system load 18. The adapter 24 may be
supplied as a component that is external to the device or system
that it is intended to supply power, and is selectively connectable
thereto.
[0022] A switch 26 connects the battery pack 22 to the system load
18 when the adapter 24 is not connected to receive ac power so that
system load 18 is powered by the rechargeable battery pack 22
directly. When the adapter 24 is connected to receive ac power,
switch 26 is opened to disconnect the rechargeable battery pack 22
from system load so that system load is powered by the ac adapter
directly. According to the embodiments described below, the
rechargeable battery pack 22 can supply additional power to the
system load 18 when the capabilities of the adapter 24 are
exceeded. More specifically, when the power required by the system
load 18 is more than the adapter 24 can provide, the buck/boost
charger system 20 may call upon the rechargeable battery pack 22 to
provide the additional power, for example by switching the
rechargeable battery pack 22 into the system by, for instance,
changing the buck converter charger to a boost converter. In
addition, when the power required by the system load 18 is higher
than that which can be provided by the adapter 24, the battery
charge current is not only reduced to zero, but the buck/boost
charger system 20 is operated in a boost mode so that the adapter
and battery power the system simultaneously.
[0023] In one embodiment, if the power demanded by the system load
18 reaches an overload condition of the adapter 24 at or exceeding
the maximum power limit of the adapter, the buck/boost charger
system 20 immediately shuts down, and waits a predetermined period,
referred to herein as a "deglitch time." After the deglitch time,
the buck/boost charger system 20 checks to determine whether the
adapter 24 is still in an overload condition, based on the total
system current. After the deglitch time, if the total system
current is still higher than the maximum current limit of the
adapter 24, the buck/boost charger system changes from buck mode to
boost mode and allows the rechargeable battery pack 22 to provide
additional power to the system load 18. As a result, the adapter 24
and the rechargeable battery pack 22 together provide sufficient
system power, thereby avoiding an adapter crash and enabling the
system load 18, including its CPU 14, to receive maximum available
power for achieving its highest performance.
[0024] With reference now additionally to FIG. 2, an electrical
schematic diagram is shown, illustrating an example of an
embodiment of a charger circuit 30 having a voltage boost function
that may be used to provide the battery charging and controlling
circuits and methods described herein. The charger circuit 30 has a
dynamic power management (DPM) circuit 32 that receives input power
on input node 34 from an adapter 24 of the type described above
which can be selectively connected thereto.
[0025] The DPM loop 32 includes an input current sensing resistor
36, the nodes on either side of which being designated "ACP" and
"ACN," which are connected as inputs to the charger control loops
38, described below in greater detail. A pair of MOSFET devices 40
and 42 are connected to receive respective high-side and low-side
driving voltages from the charger control loops 38, depending on
whether the charger is operating in buck or boost modes. An
inductor 44 is connected to the rechargeable battery pack 22 by a
charge current sensing resistor 46. The respective sides of the
charge current sensing resistor 46 are designated "SRP and "SRN,"
and are connected as inputs to the charger control loops 38, as
described in greater detail below. The power output from the
charger circuit 30 is represented by the VBUS voltage shown between
line 48 and the reference potential, or ground line 50, and by the
current source I.sub.SYS 52.
[0026] With reference now additionally to FIGS. 3A and 3B,
respectively shown are the feedback amplifier 60, duty cycle and
driver circuits 62, and boost stop and start control and circuit
64. The feedback amplifier 60 receives inputs ACP, ACN, SRP, and
SRN respectively from the input current sensing resistor 36 and
charge current sensing resistor 46, providing an input to the type
III compensation circuit 66. The output from the compensation
circuit 66 is applied to a control loop saturation determining
circuit 68 and to a PWM circuit 70. The output from the control
loop saturation determining circuit 68 is connected to the boost
stop and start circuit 64, described below, and the output from the
PWM circuit 70 is connected to the driver logic circuit 72.
[0027] The start boost and stop boost signals developed in the
boost stop and start circuit 64 are also connected as inputs to the
driver logic circuit 72. The outputs HSON and LSON signals are
connected to output drivers 74 and 76, which are level adjusted by
BTST, PHASE and REGN and GND voltages to provide drive signals to
the MOSFET devices 40 and 42 (FIG. 1) at the correct voltage
levels.
[0028] The boost start and stop circuit 64 is shown in FIG. 3B, to
which reference is now additionally made. The boost start and stop
circuit 64 receives inputs representing the voltage difference
between ACP and ACN. This voltage difference may be developed, for
example, in the feedback amplifier 60 of FIG. 3A, with appropriate
scaling.
[0029] With respect to the start boost mode, the voltage difference
between ACP and ACN is compared to a reference voltage, for example
1.05.times.VREF_IAC by comparator 80. VREF_IAC represents a
particular upper current level that is established by the host
below which operation of the adapter should be held to avoid
crashing the adapter. The comparator 80 has hysteresis so that
momentary changes in the ACP-ACN voltage difference do not cause
the comparator 80 to change state. The reference voltage is
established such that if the voltage difference ACP-ACN developed
across the input current sensing resistor 36 reaches a
predetermined percentage of the power limit of the adapter 24, in
this case 105%, the comparator 80 changes output state.
[0030] The output from the comparator 80 is connected to a delay
circuit 82 which operates to shut down the charger and begin a
predetermined delay, for example 170 .mu.s in response to the
change of state in the output of the comparator 80. If the voltage
output from the comparator 80 returns to a low value before the
predetermined delay, indicating that the boost mode is not
required, the boost mode is not initiated and the charger is turned
back on. However, after the expiration of the predetermined delay,
the start boost output changes state, triggering the driver logic
circuit 72 (FIG. 3A) to turn on the low-side MOSFET device 42 (FIG.
2) via the low-side driver 76 and high-side MOSFET device (FIG. 2)
via the high-side driver 74.
[0031] With respect to the stop boost signal, four possible input
signals can trigger the stop boost signal. The four signals are
applied to an OR gate 83, the output of which being the stop boost
signal that is applied to the driver logic circuit 72 (FIG. 3A).
The first input signal is an immediate trigger developed by
comparator 84 when the voltage difference ACP-ACN is less than a
predetermined voltage, such as 10 mV. When this condition occurs,
the boost mode is immediately shut down to prevent ACOV (system bus
over voltage). The second input signal is a trigger that occurs
when the voltage difference ACP-ACN is a predetermined percentage
below the VREF_IAC voltage level. In the example illustrated, the
percentage is 93%, and is established by the comparator 86. If the
voltage difference ACP-ACN is a predetermined percentage below the
VREF_IAC voltage level, and the output from the comparator 84 is
not high, a 1 ms delay is timed by a timer 88 to trigger the stop
boost output signal.
[0032] In addition, if the control loop is in saturation,
determined in block 90, and if the voltage difference ACP-ACN is
not a predetermined percentage below the VREF_IAC voltage level,
the stop boost output signal is triggered. Finally, a watchdog
timer 92 is provided to assure that the boost mode does not remain
engage for a predetermined time, such as 175 seconds in the example
shown.
[0033] The operation of the charger circuit 30 is illustrated in
the flow diagram 99 of FIG. 4, to which reference is now
additionally made. To enter boost mode for providing the power from
both the adapter 24 and rechargeable battery pack 22 when the
system power is higher than what the adapter can provide, a
determination is made whether the input current is greater than
105% of IDPM, diamond 100. IDPM is the current threshold setting
for the adapter so that at this threshold the charger will reduce
charging current and even give discharging current to try to
regulate adapter current at this threshold to avoid adapter
overload. For example, if a 20 V, 90 W adapter can give 4.5 A
current, and a system load is set to trigger at 4.1 A, when the
adapter current is above 4.1 A, charging current is reduced to hold
the adapter current at 4.1 A. If the adapter current is close to a
limit such as 4.4 A, the controller in the system load will
throttle to reduce CPU power, so that adapter will not see a
current higher than 4.5 A and crash. The 4.1 A is referred to as
the IDPM current (DPM dynamic power management current). Thus, the
charging current is dynamically changed based on system current, so
that the total adapter current is well regulated on or below the
IDPM set point.
[0034] If the input current is not greater than 105% of IDPM, the
determination is repeated. On the other hand, if the input current
is greater than 105% of IDPM, then the charger is immediately
shutdown, box 102. A delay of a minimum of 100 .mu.s, for example a
typical delay may be 170 .mu.s) is initiated, box 104. If the input
current is still greater than 105% of IDPM, diamond 106, then the
boost mode is started, box 108, if the other conditions are all
met. If the input current is not greater than 105% of IDPM, then
the process is reinitiated at diamond 100.
[0035] The conditions to trigger the exit from a boost mode are
shown in the flowchart 120 in FIG. 5, to which reference is now
additionally made. As described above with reference to FIG. 3B,
four conditions are concurrently monitored. As shown in diamond
122, a determination is made by comparator 84 to determine whether
the input current is above a predetermined level to prevent ACOV,
or system bus over voltage. If the input current is less than the
predetermined level, for example less than 10 mV for a 10 milliohm
sensing resistor, the boost mode is immediately shut down, box
124.
[0036] If the need for boost mode voltage no longer exists, boost
mode is also exited. Thus, a determination is made, diamond 126, by
comparator 86 whether the input current is less than a
predetermined percentage of IDPM, for example 93% in the embodiment
illustrated. If it is, a deglitch time, for example 1 ms, is timed,
box 128, after which the boost mode is exited, box 124.
[0037] On the other hand, if the input current is greater than 93%
of IDPM but is less than the input current regulation point of the
integrator, diamond 130, if the loop integrator hit saturation (see
control loop saturation determining circuit 68 in FIG. 3A and
control loop saturation box 90 in FIG. 3B) then boost mode is
exited, box 124. The delay time depends on the loop response.
[0038] Finally, if the watchdog timer 92 (See FIG. 3B) is enabled,
if timer has expired and no charge voltage or current command are
to be written, diamond 134, then the boost mode is exited, box 124.
Of course, if any of the conditions for entering the boost mode
still exist, the circuit will reenter the boost mode.
[0039] Various waveforms seen in the operation of the charger
circuit 30 of FIG. 2 are shown in FIGS. 6A-6D, to which reference
is now additionally made. The system current, I.sub.SYS, is shown
by waveform 140 in FIG. 6A, illustrating the increased system
current in DPM mode. The adapter current, I.sub.ADP, is shown by
waveform 142 in FIG. 6B, illustrating the operation of the adapter
current at the adapter current limit. The battery charge current,
ICHG, is shown by waveform 144 in FIG. 6C, illustrating the drop in
charge current due to regulation of the input current. And the
constant output voltage is shown by waveform 146 in FIG. 6D.
[0040] One of the advantages of the embodiments described herein is
that the existing battery charger topology can used, but the
control method of the embodiments may be used to allow the charger
to operate in a buck mode during the battery charging and in a
boost mode during the battery discharging for supplementing
additional power to the system. Some of the benefits realized
include allowing the CPU to operate at high speeds with the high
performance, reducing the requirement for increased adapter current
capability, eliminating extra cost for the adapter, enabling high
power conversion efficiency, reducing the total system cost, and
requiring minimum solution space.
[0041] Electrical connections, couplings, and connections have been
described with respect to various devices or elements. The
connections and couplings may be direct or indirect. A connection
between a first and second electrical device may be a direct
electrical connection or may be an indirect electrical connection.
An indirect electrical connection may include interposed elements
that may process the signals from the first electrical device to
the second electrical device.
[0042] Although the invention has been described and illustrated
with a certain degree of particularity, it should be understood
that the present disclosure has been made by way of example only,
and that numerous changes in the combination and arrangement of
parts may be resorted to without departing from the spirit and
scope of the invention, as hereinafter claimed.
* * * * *